174 BRITISH MAMMALS 



Machairodonts. They could not have died out for lack of 

 provender, or why are they not still subsisting in Africa at the 

 present day ? ^ Nor could man have been the immediate cause 

 of their extirpation as early as the Pleistocene. One can only 

 imagine that they became too heavily armed, and that the use 

 of their weapons was too intricate in a life of greater rapidity and 

 fiercer competition ; and that, while they starved, the True Cats 

 rose to power through their lither frames and less pretentious teeth. 



Family : FELIDyE. THE TRUE CATS 



These are, perhaps, the most beautiful and specialised group 

 of the Carnivora. They arose from the basal stock of the True 

 Carnivora, no doubt as a development of the Viverrids, and not 

 far from where the Weasels branched off in the Middle Eocene 

 period. In the Upper Eocene, or earlier, the primitive cats gave 

 off that remarkable branch already described as the Machairo- 

 donts. In nearly every respect the True Cats of to-day are more 

 specialised in structure than the Machairodonts, except, perhaps, 

 in the dentition and the shape of the lower jaw. In one respect 

 only are they less specialised than the modern dogs, and that 

 is the retention of the entepicondylar foramen of the humerus, 

 which is entirely absent in every member of the genus Cams. 

 On the other hand, they have lost the alisphenoid canal in the 

 base of the skull, and the femur or thigh bone is without the 

 third trochanter which is present in most Machairodonts and 

 early cats. As regards the teeth, there are always three pairs 

 of incisor teeth in both jaws. The canines are long, sharp, and 

 conical or rounded. They are proportionately longest, perhaps, 

 in the species known as the clouded tiger, and the inner edges 

 of these canines, especially in the lion and tiger, are finely 

 serrated. There are three pairs of premolars in the upper jaw, but 

 the first pair is minute, and sometimes missing (as in the lynxes). 

 The tooth answering to the fourth premolar, which is the 



1 It is remarkable that down to the present time no remains whatever of 

 any Machairodont have been obtained from any part of Africa, though they 

 are found in abundance in Europe, Asia, and North and South America. 



